It is known in the art that hydroxyaromatics may be alkylated with polybutenes and other polyolefins derived from C.sub.2 -C.sub.6 olefins to form alkylated hydroxyaromatic compounds. The alkylated hydroxy aromatic compounds such as alkylated phenol are important lubricant and fuel additives. U.S. Pat. No. 5,300,701 to Cherpeck describes the alkylation of hydroxyaromatics with polyisobutylene (PIB) in the presence of acidic alkylation catalyst to give polybutenyl hydroxyaromatic compounds. The polyisobutylene (PIB) used in the '701 patent has a methylvinylidene content of at least about 70%. The PIB used by Cherpeck had a number average molecular weight of 300-5,000.
The acidic alkylation catalysts employed by Cherpeck were Lewis acids, trifluoromethane sulfonic acid, and acidic molecular sieves. Typical acid catalysts are aluminum chloride, boron trifluoride etherate, trifluoromethane sulfonic acid and Amberlyst.RTM. molecular sieve-type catalyst. The Cherpeck 5,300,701 patent is included herein by reference in its entirety.
A concern in running PIB alkylation reactions is fragmentation of the alkylating agent and alkyl substituent. In the Cherpeck patent, this is minimized by using a high vinylidene PIB having greater than 70% methyl vinylidene terminal units in the PIB. Other solutions to minimizing fragmentation are disclosed in British Patent 1,159,368 which used boron trifluoride-phenolate at 0.degree.-65.degree. C. as the acidic alkylating catalyst.
Cahill in U.S. Pat. No. 4,238,628 reduces fragmentation of the alkylating agent by using boron trifluoride with a C.sub.3 or higher olefin polymer having a terminal ethylene unit. In the preferred mode of Cahill, polybutene is first reacted with ethylene to provide a polymer having terminal ethylene units for ease of alkylation reaction with benzene, phenol and napthol. The yields on alkylation with the ethylene-terminated polymers range from 44-64%. The Cahill U.S. Pat. No. 4,238,628 is incorporated herein by reference in its entirety.
Alkylation reactions of hydroxyaromatics with polyolefins as pointed out above rely on using a highly reactive alkylating agent having terminal unsaturation so that mild reaction conditions may be employed. The highly reactive alkylating species also provide for high yields of alkylated hydroxy aromatics. The reaction species in the Cherpeck '701 patent cited above is a terminal methyl vinylidene unit in the alkylating agent. The methyl vinylidene unit is represented by R(CH.sub.3)C.dbd.CH.sub.2 wherein R is hydrocarbyl or polymeric.
The reactive species in the Cahill '628 patent cited above is a terminal ethylene or vinyl unit RCH.dbd.CH.sub.2 which is formed by condensing a polymer such as polybutene with ethylene. R is also hydrocarbyl or polymeric.
High vinylidene PIBs as described in the '701 patent are disclosed and claimed in U.S. Pat. Nos. 4,152,499 to BASF and 4,605,808 to BP. The high vinylidene PIBs of the respective companies are sold under the trade names of Glissopal.RTM. and Ultravis.RTM.. The '499 and '808 patents are incorporated herein by reference for their disclosure of the synthesis of high vinylidene PIBs.
European Patent Specification Publication 0355 895 details the structure of isomers near the terminus of PIBs and explains reactivity of the PIBs on the basis of isomer content. EPO 0355 895 is herein incorporated by reference for material pertinent to this disclosure.
The '701 patent recites Amberlyst.RTM. 36 as a suitable catalyst for use in alkylating hydroxyaromatics with high vinylidene PIB but discloses no experimental data. Bortnick, in U.S. Pat. No. 3,037,052 discloses the use of a macro-reticular structured sulfonic cation exchanger to catalyze alkylation of phenol with C.sub.4 -C.sub.9 terminal olefins. Malloy in U.S. Pat. No. 4,323,714 describes alkylating hydroxyaromatics with C.sub.2 -C.sub.10 terminal olefins with fluoro-sulfonic acid resins available from DuPont under the trademarked name Nafion.RTM.. Similarly, U.S. Pat. No. 4,849,569 discloses alkylating aromatics including hydroxyaromatics with C.sub.2 -C.sub.20 olefins with zeolite-type catalysts and sulfonated ion exchange catalysts such as Amberlyst.RTM. 15. There is no disclosure of experimental detail in the '569 patent of Amberlyst.RTM. 15, hydroxyaromatic, olefin reaction product. U.S. Pat. Nos. 5,019,669 and 5,080,871 also describe using C.sub.2 -C.sub.20 olefins to alkylate aromatics including hydroxyaromatics using zeolites and sulfonated ion exchange resins. The olefins used have terminal unsaturation.